Plate-type heat pipe

ABSTRACT

An exemplary plate-type heat pipe includes a hermetic container, working fluid contained in the container, a first wick portion and two second wick portions formed on inner surfaces of the container. The container includes an evaporating plate and a condensing plate facing each other. The evaporating plate includes a heat absorbing portion, two transition portions extending outwardly and upwardly from opposite ends of the heat absorbing portion, respectively, and two extending portions extending outwardly from outer ends of the transition portions, respectively. The first wick portion is formed on an inner surface of the heat absorbing portion. The second wick portions are formed on inner surfaces of the transition portions, respectively. The third wick portions are formed on inner surfaces of the extending portions, respectively. The third wick portions define capillary pores and a plurality of holes therein.

BACKGROUND

1. Technical Field

The present disclosure relates to heat pipes and, more particularly, to a plate-type heat pipe having good heat dissipation efficiency and stable and reliable performance.

2. Description of Related Art

Generally, plate-type heat pipes efficiently dissipate heat from heat-generating components such as a central processing unit (CPU) of a computer. A conventional plate-type heat pipe comprises a top plate and a bottom cover hermetically contacting the top plate to form a container. A wick structure is adhered to an inner surface of the bottom cover. Working fluid is contained in the container. All parts of the wick structure have the same thickness. When the bottom cover of the plate-type heat pipe absorbs heat of the heat-generating component, the working fluid is vaporized to absorb the heat of the bottom cover.

If the wick structure is too thick, a part of the vaporized working fluid is retarded by the wick structure when the vaporized working fluid is escaping from the wick structure toward the top plate. Therefore, a plurality of bubbles is formed in and on the wick structure. The bubbles tend to block pores of the wick structure, and retard the flow of condensed working fluid into the wick structure. When this happens, the amount of condensed working fluid contained in the wick structure decreases. What working fluid there is in the wick structure may absorb the heat of the bottom cover too slowly, whereby heat is accumulated on the bottom cover, and the plate-type heat pipe overheats. Conversely, if the wick structure is too thin, the working fluid contained in the wick structure is liable to be dried off altogether. When this happens, the plate-type heat pipe will be destroyed.

What is needed, therefore, is a plate-type heat pipe having good heat dissipation efficiency and stable, reliable performance.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, all the views are schematic.

FIG. 1 is a cross-sectional view of a plate-type heat pipe in accordance with a first embodiment of the present disclosure, the plate-type heat pipe including an evaporating plate having two extending portions, and two wick portions arranged on the extending portions.

FIG. 2 is an isometric view of part of one of the wick portions arranged on the corresponding extending portion of FIG. 1.

FIG. 3 is an enlarged, cross-sectional view of part of the wick portion and extending portion of FIG. 2, taken along line III-III thereof.

FIG. 4 is similar to FIG. 3, but showing part of an extending portion arrangement of an evaporating plate of a plate-type heat pipe in accordance with a second embodiment of the present disclosure, with a wick portion and a number of auxiliary wick portions received in the wick portion.

FIG. 5 is similar to FIG. 3, but showing part of an extending portion arrangement of an evaporating plate of a plate-type heat pipe in accordance with a third embodiment of the present disclosure, with a wick portion and a number of auxiliary wick portions received in the wick portion.

FIG. 6 is similar to FIG. 3, but showing part of an extending portion arrangement of an evaporating plate of a plate-type heat pipe in accordance with a fourth embodiment of the present disclosure, with a wick portion and a number of auxiliary wick portions received in the wick portion.

FIG. 7 is an isometric view of a wick member of an evaporating plate of a plate-type heat pipe in accordance with a fifth embodiment of the present disclosure.

DETAILED DESCRIPTION

Referring to FIGS. 1-2, a plate-type heat pipe in accordance with a first embodiment of the present disclosure is shown. The plate-type heat pipe includes a hermetic container 10, a continuous wick structure 30 mounted on an inner surface of the container 10, and working fluid (not shown) contained in the container 10.

The container 10 is made of copper, aluminum, or an alloy thereof. The container 10 includes an elongated condensing plate 11 and a bowl-shaped evaporating plate 13 integrally formed as a single, one-piece, monolithic body without any seams. The evaporating plate 13 absorbs heat of heat-generating components (not shown) such as electronic devices. Then the condensing plate 11 dissipates the heat, transferred from the evaporating plate 13, to the ambient environment. In alternative embodiments, the elongated condensing plate 11 and the bowl-shaped evaporating plate 13 can be distinct pieces, with the bowl-shaped evaporating plate 13 hermetically contacting the condensing plate 11.

The evaporating plate 13 includes an elongated heat absorbing portion 131, two transition portions 133, two extending portions 134, and two sidewalls 135. The two transition portions 133 extend upwardly and outwardly from opposite lateral edges of the heat absorbing portion 131, respectively, and are symmetrically opposite each other. The two extending portions 134 extend outwardly along opposite horizontal directions from outer edges of the transition portions 133, respectively. The sidewalls 135 extend upwardly from outer edges of the extending portions 134, respectively. The sidewalls 135 are perpendicular to the extending portions 134. The extending portions 134 are parallel to the heat absorbing portion 131, and are closer to the condensing plate 11 than the heat absorbing portion 131. In the illustrated embodiment, top ends of the sidewalls 135 are integrally formed with two ends of the condensing plate 11. That is, the evaporating plate 13 and the condensing plate 11 are a single body of the same material without any seams. In other embodiments, the evaporating plate 13 and the condensing plate 11 can be separate bodies hermetically connected together.

The wick structure 30 is made of sintered metallic powder, and includes an elongated first wick member 31 and a second wick member 33. The first wick member 31 is adhered to an inner surface of the condensing plate 11. The second wick member 33 is adhered to an inner surface of the evaporating plate 13. The second wick member 33 is adapted for providing a capillary force to draw condensed working fluid from the first wick member 31 back toward a middle portion of the second wick member 33. Opposite ends of the second wick structure 33 interconnect opposite ends of the first wick member 31, respectively, thereby forming the continuous wick structure 30.

Referring also to FIG. 3, the second wick member includes an elongated first wick portion 331, two second wick portions 333, two third wick portions 335, and two fourth wick portions 337. The first wick portion 331, the second wick portions 333, and the third wick portions 335 are spaced from the first wick member 31.

The first wick portion 331 is adhered to an inner surface of the heat absorbing portion 131 of the evaporating plate 13. The second wick portions 333 extend upwardly and outwardly from opposite ends of the first wick portion 331, respectively, and are symmetrically opposite each other. The second wick portions 333 are adhered to inner surfaces of the transition portions 133 of the evaporating plate 13. The first wick portion 331 is thinner than each of the second wick portions 333 and each of the third wick portions 335. Thus, in general, the working fluid contained in the first wick portion 331 is vaporized faster than working fluid at a comparable location in a conventional plate-type heat pipe. Accordingly, the heat of the heat absorbing portion 131 is transferred quickly. The third wick portions 335 are horizontal, and extend outwardly from the second wick portions 333, respectively. The third wick portions 335 are adhered to inner surfaces of the extending portions 134 of the evaporating plate 13. The fourth wick portions 337 are adhered to inner surfaces of the sidewalls 135 of the evaporating plate 13, and perpendicularly connect outer ends of the third wick portions 335, respectively.

Each of the third wick portions 335 defines a plurality of rectangular or square through holes 3353 therein. In the illustrated embodiment, the through holes 3313 are arranged in a regular m×n array. The working fluid contained in the first wick portion 331 absorbs the heat of the heat absorbing portion 131 quickly, and then is vaporized. The vaporized working fluid moves to the first wick member 31 to dissipate the heat, and condenses at the first wick member 31. The fourth wick portions 337, third wick portions 335, and second wick portions 333 cooperatively guide the condensing working fluid contained in or accumulated on the first wick member 31 back to the first wick portion 331. Because the through holes 3353 are defined in the third wick portions 335, a portion of the condensing working fluid is contained in the through holes 3353. Thus, the amount of working fluid contained in the second wick member 33 is increased relative to working fluid at a comparable location in a conventional plate-type heat pipe. The working fluid contained in the through holes 3353 can ensure that a quantity of the condensing working fluid in the first wick portion 331 is sufficient even though evaporation of the working fluid in the first wick portion 331 is faster. Therefore, the plate-type heat pipe avoids becoming dried off. Thus, the plate-type heat pipe has stable, reliable performance. In alternative embodiments, the through holes 3353 can be triangular, circular, oval-shaped, elliptical, etc.

Referring to FIG. 4, this shows an extending portion arrangement of a plate-type heat pipe in accordance with a second embodiment of the present disclosure. A third wick portion 335 and a plurality of auxiliary wick portions 332 are adhered to an inner surface of an extending portion 134. The plate-type heat pipe in accordance with the second embodiment, is substantially the same as that shown in FIG. 1, except the auxiliary wick portions 332. Therefore a detailed description of most parts of the structure of the plate-type heat pipe in accordance with the second embodiment is omitted. In the illustrated embodiment, the auxiliary wick portions 332 fill bottom ends of through holes 3353, respectively. Bottom end surfaces of the auxiliary wick portions 332 and a bottom surface of the third wick portion 335 are coplanar with one another, and are adhered to the inner surface of the extending portion 134. The auxiliary wick portions 332 have the same thickness, and are much thinner than the third wick portion 335. For example, each auxiliary wick portion 332 is less than half the thickness of the third wick portion 335.

Because the auxiliary wick portions 332 are much thinner than the third wick portion 335, a majority of each of the through holes 3353 is available to accommodate working fluid. The condensing working fluid is contained in pores of the second wick member 33 and the upper portions of the through holes 3353 not occupied by the auxiliary wick portions 332. Therefore, a quantity of the condensing working fluid in the second wick member 33 is increased relative to working fluid at a comparable location in a conventional plate-type heat pipe. In addition, a capillary force of the second wick member 33 is improved because of the auxiliary wick portions 332 filling the bottoms of the through holes 3353 of the third wick portion 335. Therefore, the condensed working fluid flows back to the first wick portion 331 more quickly. Thus, stable and reliable performance of the plate-type heat pipe can be ensured.

Referring to FIG. 5, this shows an extending portion arrangement of a plate-type heat pipe in accordance with a third embodiment of the present disclosure. A third wick portion 335 and a plurality of auxiliary wick portions 334 are adhered to an inner surface of an extending portion 134. A difference between the plate-type heat pipe of the third embodiment and the plate-type heat pipe shown in FIG. 4 is only in the shape of the auxiliary wick portions 334. In the third embodiment, a cross-section of each of the auxiliary wick portions 334 is a trapezoid. Each auxiliary wick portion 334 has a smaller end, and a larger end opposite to the smaller end. The smaller ends of the auxiliary wick portions 334 are all oriented toward the same direction. A top side of each auxiliary wick portion 334 is aslant, and a bottom side of each auxiliary wick portion 334 is horizontal and adhered to the inner surface of the extending portion 134. The larger ends of the auxiliary wick portions 334 are all thinner than the third wick portion 335.

Referring to FIG. 6, this shows an extending portion arrangement of a plate-type heat pipe in accordance with a fourth embodiment of the present disclosure. A third wick portion 335 and a plurality of auxiliary wick portions 336 are adhered to an inner surface of an extending portion 134. A difference between the plate-type heat pipe of the fourth embodiment and the plate-type heat pipe shown in FIG. 4 is only in the shape of the auxiliary wick portions 336. In the fourth embodiment, a cross-section of each of the auxiliary wick portions 336 has a top side being concave, and a bottom side being horizontal. The bottom sides are adhered to the inner surface of the extending portion 134. A thickness of each auxiliary wick portion 336 gradually increases from a central portion thereof to each of opposite ends thereof. The opposite ends of the auxiliary wick portions 336 are all thinner than the third wick portion 335.

Referring to FIG. 7, this shows a second wick member 73 of a plate-type heat pipe of a fifth embodiment of the present disclosure. The second wick member 73 is similar to the second wick member 33 of the first embodiment, except that a plurality of rectangular or square through holes 7313 is defined in a first wick portion 731. Therefore the vaporized working fluid in the first wick portion 731 escapes from the first wick portion 731 via the through holes 7313 quickly. Accordingly, unlike in conventional plate-type heat pipes, few or even no bubbles accumulate in the first wick portion 731 when the plate-type heat pipe is in operation. Thus, the heat dissipation efficiency of the plate-type heat pipe is improved.

It is to be understood, however, that even though numerous characteristics and advantages of various embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. 

1. A plate-type heat pipe comprising: a condensing plate; an evaporating plate cooperating with the condensing plate to define a hermetic container, the evaporating plate comprising a heat absorbing portion and two extending portions located at opposite sides of the heat absorbing portion; working fluid contained in the container; and a first wick portion formed on an inner surface of the heat absorbing portion, and two second wick portions formed on inner surfaces of the extending portions, respectively, the second wick portions defining a plurality of holes therein.
 2. The plate-type heat pipe of claim 1, wherein the holes are through holes, each of which extends through a thickness of the corresponding second wick portion.
 3. The plate-type heat pipe of claim 2, wherein a number of auxiliary wick portions are received in the through holes, respectively, and contact the inner surfaces of the extending portions.
 4. The plate-type heat pipe of claim 3, wherein each of the auxiliary wick portions is thinner than the second wick portion, and comprises a first side contacting the inner surface of the corresponding extending portion of the evaporating plate and an opposite second side.
 5. The plate-type heat pipe of claim 4, wherein a cross-section of each of the auxiliary wick portions is a rectangle, the second side being parallel to the first side.
 6. The plate-type heat pipe of claim 4, wherein a cross-section of each of the auxiliary wick portions is a trapezoid, the second side being aslant relative to the first side.
 7. The plate-type heat pipe of claim 6, wherein the auxiliary wick portions are all oriented toward the same direction.
 8. The plate-type heat pipe of claim 4, wherein the second side of each of the auxiliary wick portions is concave, and a thickness of each of the auxiliary wick portions gradually increases from a central portion thereof to each of opposite ends thereof.
 9. The plate-type heat pipe of claim 1, wherein the evaporating plate further comprises two transition portions extending upwardly and outwardly from opposite edges of the heat absorbing portion and connecting with the two extending portions, respectively, and two third wick portions are formed on inner surfaces of the transition portions, respectively.
 10. The plate-type heat pipe of claim 1, wherein the evaporating plate further comprises two sidewalls extending upwardly from outer ends of the two extending portions, respectively, and connecting with the condensing plate, and two fourth wick portions are formed on inner surfaces of the sidewalls, respectively.
 11. The plate-type heat pipe of claim 10, wherein a wick member is adhered on an inner surface of the condensing plate and connects with the fourth wick portions.
 12. The plate-type heat pipe of claim 1, wherein a plurality of holes is defined in the first wick portion.
 13. A plate-type heat pipe comprising: a hermetic container comprising an evaporating plate and a condensing plate facing each other, the evaporating plate comprising a heat absorbing portion adapted for contacting a heat-generating component, two transition portions extending aslant from opposite lateral sides of the heat absorbing portion, respectively, and two extending portions extending outwardly from outer sides of the transition portions, respectively, the extending portions being closer to the condensing plate than the heat absorbing portion; working fluid contained in the container; and a wick member formed on an inner surface of the evaporating plate, comprising a first wick portion formed on an inner surface of the heat absorbing portion, two second wick portions formed on inner surfaces of the transition portions, respectively, and two third wick portions formed on inner surfaces of the extending portions, respectively, the third wick portions defining a plurality of holes.
 14. The plate-type heat pipe of claim 13, wherein the holes extends through the third wick portions in the thickness direction of the third wick portions.
 15. The plate-type heat pipe of claim 14, wherein a plurality of auxiliary wick are arranged in the holes of the third wick portions and contacts the inner surfaces of the extending portions.
 16. The plate-type heat pipe of claim 15, wherein each of the auxiliary wicks is thinner than the third wick portion.
 17. The plate-type heat pipe of claim 15, wherein the evaporating plate further comprises two sidewall extending upwardly from outer ends of the extending portions, respectively and connect opposite ends of the condensing plate, respectively, two fourth wick portion are formed on inner surfaces of the sidewalls.
 18. The plate-type heat pipe of claim 17, wherein another wick member is adhered on an inner surface of the condensing plate and connects with the fourth wick portions to form a continuous wick on an inner surface of the container.
 19. The plate-type heat pipe of claim 13, wherein the first wick portion is thinner than second wick portion and the third wick portion.
 20. The plate-type heat pipe of claim 19, wherein a plurality of holes is defined in the first wick portion. 